If you want to clean the root ball, you would need to either unpot it and wash off all the soil. Or you can immerse the entire plant in some water with a few drops of Dawn dish soap. Let it sit in that water for about 10 minutes. Then rinse thoroughly with fresh water and let it dry.

Mealies can be insidious.

why did you buy it.. if it was infested ...

and why not just return it??

I do not see any mealies, but I know hoyas tend to have them.

Just wanted to do some cleaning while it was in quarantine

If you haven't seen any sign of mealies, I would just spray it with neem or diluted alcohol. Then rinse with clear water. Quarantine the plant away from your other plants for several weeks and watch for any sign of mealies.

Sometimes "over-preventing" can do more harm than good.

I soak any of mine under warm soap water for at least 20 minutes and you will have killed them in the soil as well as on the plant and pot.

I did an experiment the other day. I had some cuttings. Some had roots, some did not. Since I have a history of mealybug, I put all the cuttings into a dish tub with some Dawn dishwashing liquid. I let them soak in that water for 20 minutes. Then removed them and let them dry. And unbelievable to me, there were still some live mealies. They are just sinister. After that, I went and purchased some Bayer Dual Action Rose & Flower Insect Killer. It contains imidacloprid. Next time, that's what they are going to get!

Were your bugs exposed to radiation? That’s crazy!! Sinister they are. Ha

I agree with what Popmama said earlier - if you don't see any, then just isolate for a few weeks and recheck. Not all hoyas come with mealies. The ones you do see are easily taken care of with a q-tip dipped in alcohol and dabbed on the bug. It'll instantly die. Then a preventative treatment with neem oil may be in order.

I keep all my plants outside for the summer. occasionally I'll see a mealy, but usually the predators do a great job of removing them. Once everything comes inside in the September October time frame, I'm good until about February, then any survivors start to pop out. They get dabbed with alcohol till I can get them outside again in late April - May time frame, and the process starts all over again.

Don't obsess over them, just treat them when you find them and you'll be fine.